The present invention relates generally to air-launched stores, and more particularly to a gliding sonobuoy suitable for launching from an aircraft to diverse locations in the sea relative to the flight path.
Certain undersea detection and surveillance operations employ a long field of acoustic sensors created by launching a series of expendable sonobuoys at spaced intervals from an aircraft over a sea area of interest. The sonobuoys are typically ejected from launch tubes and retarded during descent by an air brake mechanism or drogue chute. As expected, the terminal positions of the sonobuoys are in a line generally parallel to the flight path of the aircraft except for slight deviations due to transitory changes in wind speed and direction. Sonobuoys retarded by air brakes will usually land in a narrow path close to the flight path, while sonobuoys with drogue chutes may drift with the air currents and land in a narrow path offset from the flight path.
In some surveillance missions, a relatively wide path of dispersion is desired. From an operational point of view, of course, it is advantageous to accomplish this in a single pass of the "seeding" aircraft. In addition to saving flight time and fuel consumption, the time required to lay out the array in proportion to the operational life-span of the sonobuoy is significantly reduced, and the accuracy of the dispersion pattern is improved since both local sea and atmospheric conditions have less time to influence the terminal position of each sonobuoy. To produce a wide dispersion path in a single pass, it is necessary for each sonobuoy to be guided to the right or left of the aircraft's flight path as it descends. For example, U.S. Pat. No. 5,042,744 to Bruce W. Traver et al. discloses an air-launched store which has a collapsed cylindrical steering ring that expands around the small end of a truncated conical container after the store is ejected from a launch tube. The ring is angularly and longitudinally positioned relative to the container to provide aerodynamic stability and a predetermined direction of flight.
To operate as a radio-linked sonobuoy, the store must also have sufficient buoyancy when in the sea to support an antenna above the surface in order to transmit and receive. High sea states, in particular, require supplemental flotation in the sonobuoy, such as an inflated bag with an enclosed antenna, in order to ensure that the antenna stays above the surface for uninterrupted communications.
Heretofore, separate and discrete steering and flotation components have been utilized in air-launched sonobuoys to achieve both a wide field of dispersion in a single pass of the aircraft and sufficient buoyancy for uninterrupted transmission of radio signals after landing in the sea.